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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8768
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a 3 yr old Lennox icomfort system. Today the screen

Customer Question

I have a 3 yr old Lennox icomfort system. Today the screen is blank. It doesn't look like it takes batteries. The wi fi is fine. The ac unit looks ok, no frost buildup. I checked the circuit breaker and it wasn't thrown. Help. It is very hot here.
Submitted: 1 year ago.
Category: HVAC
Expert:  Phil replied 1 year ago.

Hello, tell me a lot about your technical skill sets and if you have a multi meter or not so that I can coach you most efficiently

Customer: replied 1 year ago.
Somewhat mechanically inclined, but don't have a multi meter.
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** front portion of the thermostat gently from its wall mounting plate,

you will see the thermostat wires connected to various terminals marked R, Y, W, G and etc

Tell me which color wires go to which terminals and I will prescribe some tests that you can do.

Customer: replied 1 year ago.
I have been trying to, I'm afraid I will break it. There are small tabs on the bottom, and I can't seem to budge it. I will try again.
Expert:  Phil replied 1 year ago.

See if you can push the tabs at the bottom in slightly and release the bottom if that works then lift thermostat up and out

(when prying you need to pry in the tiny gap between the wall mounted plastic plate and the operating front end of the thermostat... do not try to pry the wall plate off of the wall)...if you are in the right spot it should move fairly easily, then work your way around the perimeter evenly until you separate the front end from the wall plate mount,)

Customer: replied 1 year ago.
There are 4 wires and they all go into the wall. There are four posts on the back of the thermostat unit, each has a letter- L-R
C i- i+ RThe Red goes to the R, the Yellow to the i+, the white to the i- and the Blue to the CI don't know if that is making any sense at all
Expert:  Phil replied 1 year ago.

Good work, that is a special type of thermostat, I need the brand and model number of it, that is inked in on the back of the thermostat as you are holding it in your hand,

Customer: replied 1 year ago.
Lennox icomfort Wi-Fi
Catalog# *****
Part# *****
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** a communicating type thermostat, (means the thermostat has a micro computer that monitors the furnace and AC unit performance against the room air temperature conditions and fine tunes the system accordingly).

It is nothing that can repair your self. The most you can do is to check for 24volts between R and C...that would tell us if you have a burned out 24v transformer or fuse in that circuit or not,

There is nothing we can jumper to test the system as with conventional thermostats.


that is the manual for what its worth. You will have to call the dealer on this one.

Let me know if you are happy with them or not, if not I can look for a better qualified dealer in your area.

Customer: replied 1 year ago.
My husband just checked with the multi meter, and there is 24 v across R and C. Lets hope for a quick and easy solution, it is 88 degrees in the bedroom. Thanks for your help
Expert:  Phil replied 1 year ago.

Thanks, ***** ***** like the thermostat display has failed... testing other causes is quite complex, most techs would just replace the thermostat. With Lennox this is something that they must do, sorry about that... but that is the situation with lennox, they like to make proprietary equipment.

Stay in touch if you have any trouble at all contacting or working with the dealer who installed the system,